过滤器、监听器、拦截器三大组件+定时器

蔚落 2022-03-17 03:16 261阅读 0赞

前文：

javaweb+ssm中比较重要的三大器。

配合SSM框架的初步解析[https://blog.csdn.net/weixin\_42687074/article/details/89004065][https_blog.csdn.net_weixin_42687074_article_details_89004065]食用更加

一、过滤器

1.概念

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70][]

2.使用方式

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 1][]

3.过滤器配置及过滤链

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 2][]

4.代码实现

实现类
    
    public class EncodingFilter implements Filter{
        
        //其他代码
    
        @Override
        public void doFilter(ServletRequest request, ServletResponse response,
    		FilterChain chain) throws IOException, ServletException {
        	//代码块
        	chain.doFilter(req, response);
        }
    
    }
    
    web.xml配置文件
    
     
     <filter>
     	<filter-name>EncodingFilter</filter-name>
     	<filter-class>cn.tedu.filter.EncodingFilter</filter-class>
     </filter>
     <filter-mapping>
     	<filter-name>EncodingFilter</filter-name>
     	<url-pattern>/*</url-pattern>
     </filter-mapping>

二、监听器

1.概念

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 3][]

2.八大监听器接口

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 4][]

3.代码实现

监听器类
    import javax.servlet.ServletContextListener;
    
    public class MyServletContextListener implements ServletContextListener {
    
    	@Override
    	public void contextInitialized(ServletContextEvent sce) {
    		// 向application作用域中添加一个键值对 app，web应用映射的虚拟路径
    		ServletContext sc=sce.getServletContext();
    		String path=sc.getContextPath();
    		sc.setAttribute("app", path);
    	}
    
    	@Override
    	public void contextDestroyed(ServletContextEvent sce) {
    		// TODO Auto-generated method stub
    	}
    
    }
    
    web.xml配置文件
    
     <listener>
     	<listener-class>cn.tedu.listener.MyServletContextListener</listener-class>
     </listener>

4.对比ssm框架监听器

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 5][]

三、拦截器

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 6][]

在springboot中的拦截器

1.在pom.xml中在spring-boot-starter-web继承

2.在启动类中添加@ImportResource(value="classpath:spring\_mvc.xml")扫描xml配置文件

3.拦截器启动类com\\jt\\mall\\web\\WebInterceptors.java

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 7][]

四、定时器

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 8][]

在springboot中的定时器

1.在pom.xml中添加需要的jar包依赖

2.在启动类中添加@ImportResource(value="classpath:spring\_quartz.xml")扫描xml配置文件

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MjY4NzA3NA_size_16_color_FFFFFF_t_70 9][]

五、备注

1.过滤器与拦截器的对比

过滤器侧重于对请求数据的处理，拦截器侧重于访问权限的控制

[https_blog.csdn.net_weixin_42687074_article_details_89004065]: https://blog.csdn.net/weixin_42687074/article/details/89004065
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